Coincidentally I've just bought the Spyder 2 today and just finished calibrating my Eizo L768 display (I've just realised even that's an L)):o It's somewhat dependant on the monitor controls as some have more than others available for tweaking the settings.
It didn't make a huge difference but it was visible. So in one way it's comforting to think that I must have set it up reasonably close to optimum manually. I think the main thing is that it should give a known setting to be able to return to. By the looks of it, the major differences between the Spyder express, Spyder 2 and the Spyder Pro seems to be the software with the actual Spyder itself being the same unit. I don't suppose it compares to a true spectrophotometer (we use them at work for colour matching) but they cost a LOT more and it's hardly justifiable for my use.
So... possibly a litte early to comment more, but so far I'm pleased with it and certainly don't regret buying it.
Hope that helps a little anyway,
Cheers
Bill